title: UVB-induced epidermal hyperproliferation is modified by a single, topical treatment with a mitosis inhibitory epidermal pentapeptide.
abstract: A single application of a water-miscible cream base containing the recently identified mitosis inhibitory epidermal pentapeptide pyroGlu-Glu-Asp-Ser-GlyOH (EPP) to hairless mouse skin is followed by a long-lasting period of reduced epidermal cell proliferation. To examine if a similar growth inhibition could be achieved in stimulated and rapidly proliferating epidermis, EPP was applied at two different concentrations, 0.005 or 0.02%, to hairless mouse skin immediately after exposure of the left flank to an erythemic dose of ultraviolet B light (UVB). This dose of UVB alone induces a sustained period of rapid epidermal cell proliferation, starting at about 18 h after the irradiation. Epidermal cell proliferation was followed from 18 to 54 h (0.005% cream) or from 18 to 30 h (0.02% cream) after the treatment by estimating the rate of G2-M cell flux (the mitotic rate) by means of Colcemid, and epidermal DNA synthesis by counting labeled cells after pulse-labeling with 3H-thymidine. The unirradiated side of the mice was used as reference. The results showed that topical treatment with a 0.02% EPP cream partially inhibited UVB-induced epidermal hyperproliferation, while the 0.005% EPP cream inhibited as well as stimulated the UVB-induced hyperproliferation. Thus, EPP is effective even in rapidly proliferating epidermal cell populations, but the outcome is obviously dose-dependent in this test system.
authors.affiliation: Institute of Pathology, University of Oslo, Rikshospitalet, Norway.
authors.forename: W M
authors.initials: WM
authors.lastname: Olsen
authors.forename: K
authors.initials: K
authors.lastname: Elgjo
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D000078404:Epidermal Cells; D005260:Female; D006131:Growth Inhibitors / Q000494:pharmacology; D051379:Mice; D008812:Mice, Hairless; D008938:Mitosis / Q000187:drug effects; D009842:Oligopeptides / Q000494:pharmacology*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D006131:Growth Inhibitors; D009842:Oligopeptides; C050550:epidermal pentapeptide; D011761:Pyrrolidonecarboxylic Acid